THE WHEAT GRAIN AND PLANT 



25 



Chemistry. The five outer layers of the wheat grain are 

 composed chiefly of cellulose, a woody, fibrous substance. The 

 endosperm, the food part of the grain, contains large quantities 

 of starch, a nitrogenous substance known as gluten, a little 

 sugar, and the cellulose of its cell walls. The gluten content 

 is greatest at the hard exterior of the endosperm. The softer 

 center makes better flour, however^ \f or it remains freer from 

 the bran in the grinding. The germ is composed of cellulose, 

 nitrogenous substances, and about !(} per cent of fat. 



The following table gives in per cents of the entire weight 

 the comparison of different kinds and commercial grades of 

 wheat, and of wheat straw and chaff. 



SOMPARISONS OF GRADES OF WHEAT, WHEAT STRAW AND CHAFF. 



1 U. S. Dept. Agr., Office Exp. Sta,, Exp. Sta. Bui. 11, pp. 106-118. 



2 N. D. Bui. 8, p. 6. Average results from many analyses. 



3 Kept. N. D. Exp. Sta., 1903, p. 26. Data from N. D. wheat crop 

 of 1901. 



4 Johnson, How Crops Grow, pp. 386-387. 



6 Kept. Canada Exp. Farms, 1900, p. 182. 1899 crop grown in the 

 N. W. Terrs. 



6 Church, Food Grains of India, p. 95. 



7 An average from Dak. Stations, U. S. Dept. Agr., Farm Bui. 

 139, p. 11. 



8 Rept. N. D. Exp. Sta.. 1904. p. 33 



